Technical Field
The invention relates to an impeller and fan.
Related Art
Fans can be classified into axial fan and centrifugal fan according to direction relationship between fan inlet and outlet. In ordinary axial fan, airflow flows into the inlet and flows out from the outlet. The airflow into the inlet and the airflow from the outlet flow toward almost the same direction.
Generally, an axial fan is designed by stacking 2-4 sections of fan blades based on NACA 4-digit or 5-digit airfoil. These airfoils at different sections are continuously connected by lines and surfaces to form a three-dimensional blade. However, this design method can not easily give enough detail description of the surface of the fan blade. Moreover, to hold curvature continuity of fan blade, it is not easy to add extra variation on segments of the fan blade. Moreover, the maximum orientation angle of the blade of the traditional quiet fan is between 25 degrees to 36 degrees. If applying greater orientation angle, fan characteristics becomes worse instead.